2,4,5-Triphenyl-, 2,4,5-tris(4-chlorophenyl) -and 2,4,5-tris(4-methylphenyl)-derivatives of imidazoline are known [Merck Index 9, 51, Chroachica Chemica Acta, 45, 519 (1973) and Canadian Journal of Chemistry 50, 669 (1972)]. Among them, the 2,4,5-triphenylderivative is known to show cardiac inhibitory effect, but there have been known no pharmacological effect of the other two derivatives.